\documentclass[a5paper,twoside,12pt]{book}
\input{preamble}
\begin{document}
\pagenumbering{Roman}
\title{\font\x="Sanskrit 2003:script=deva,mapping=tex-text" at 40pt \x सङ्क्षेपरामायणम्}
\date{}
\author{}
\maketitle
\clearemptydoublepage
\setmainfont{Sanskrit 2003:script=deva}
%\large
\Large

\pagenumbering{arabic}
\sectionmark{\mbox{}}
\begin{center}
\setcounter{page}{1}
\input{"sankshepa ramayana.tex"}
\end{center}
\end{document}